A generic electromechanical servo steering system has an electric servomotor which drives a worm shaft which meshes with a worm wheel arranged on a steering shaft, wherein the worm wheel is operatively connected to an input shaft of a steering gear mechanism, and wherein the worm shaft and the steering shaft are rotatably mounted in a common gear mechanism housing.
The laid-open specification WO 2012/136315 discloses an arrangement in which the position of the worm shaft relative to the worm wheel is adjustable. In this case, the adjustment is performed by way of an actuator or a spring preload with the aid of a motion link on that side of the worm shaft which is “remote from the motor”, whereas the mounting of the worm is realized at the motor side. The adjustment of the position of the worm shaft relative to the worm wheel makes it possible to correct the play that arises, for example as a result of wear, during operation.
It is desirable for the worm wheel to be run in in the installed state. For this purpose, the worm must be subjected to a significantly greater preload, which is however possible only in the case of motor-side attachment of the motion link.
EP 2 497 975 has disclosed a pressure-exerting device which is mounted at the motor side and in the case of which a torsion spring is situated concentrically with respect to the worm axis and which drives an eccentric apparatus.